title: Genetic and biochemical properties of thialysine-resistant mutants of Saccharomyces cerevisiae.
abstract: Three groups of lysine-excreting, thialysine-resistant mutants of Saccharomyces cerevisiae were derived from the wild-type strain (X2180) by mutagenic treatment and selected on the basis of a cross-feeding assay. Mutants MNNG2-9, MNNG2-27, MNNG2-39 and MNNG2-62 (group 1) exhibited a 2:2 segregation for thialysine resistance following mating with a wild-type strain and a lower than wild-type lysyl-tRNA synthetase activity; the thialysine-resistant phenotype was dominant in specific hybrids. Mutant MNNG2-2 (group II) was similar to group I mutants except that the thialysine-resistant phenotype was recessive in the hybrid. Mutant MNNG3-142 (group III) exhibited an irregular ratio of segregation of thialysine resistance and a significantly lower lysyl-tRNA synthetase activity; the thialysine-resistant phenotype was recessive in the hybrid. The growth of both group I and group III mutants was temperature-sensitive. The thialysine-resistant mutants exhibited pleiotropic properties including the increased production and excretion of lysine, thermosensitive growth and an impairment of lysyl-tRNA synthetase activity.
mesh_terms: D003545:Cysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D005799:Genes, Dominant; D005808:Genes, Recessive; D008239:Lysine / Q000096:biosynthesis; D008250:Lysine-tRNA Ligase / Q000378:metabolism; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D013696:Temperature
chemical_list: C000204:S-2-aminoethyl cysteine; D008250:Lysine-tRNA Ligase; D008239:Lysine; D003545:Cysteine